Computer networks typically utilize a TCP/IP (Transmission Control Protocol/Internet Protocol) protocol stack or equivalent protocol to provide addressing, as well as to provide error control and flow control. See, e.g., Internet Engineering Task Force Request For Comment (IETF RFC) 791, Internet Protocol, and IETF RFC 793, Transmission Control Protocol. The IP protocol will deliver a packet independently of all other packets; however, the IP protocol does not guarantee delivery of a packet. Among other things, the TCP protocol is utilized to provide guaranteed delivery of a packet. The TCP protocol performs addressing and also provides both error control and flow control. Because the IP protocol does not, by itself, guarantee delivery, thereby necessitating the implementation of a separate protocol (e.g., TCP) for reliable data transfer, there is increased overhead associated with TCP/IP software stack processing. Thus, the TCP/IP protocol stack is a significant source of delay in computer networks, resulting in increased packet latency.
For a web server, or server cluster, hosting an Internet site, the packet latency associated with the TCP/IP stack is particularly troublesome, especially for those Internet sites providing business services (e.g., sales, auctions, brokerage services, etc.). TCP/IP stack processing can lead to delays in communications between a web server and a client, as well as to delays in inter-processor communications amongst a group of servers in a cluster. Web servers and server clusters are becoming one of the largest sources of delay in Internet communications—with most of the server latency being attributed to TCP/IP stack processing—making the web server (or server cluster) the primary bottleneck in Internet transactions. Client-server communication delays resulting from such packet latency can lead to poor site performance (e.g., slow response time) and low availability, and a lack of client access may lead to frustrated customers and/or lost revenue.
One technology that has emerged in recent years to overcome the problems associated with TCP/IP stack processing delays in server clusters is the InfiniBand® Architecture (IBA). See InfiniBand Architecture Specification Volume 1, Release 1.0.a, June 2001, and InfiniBand Architecture Specification Volume 2, Release 1.0.a, June 2001. The InfiniBand® specifications describe an interconnect technology for interconnecting nodes—e.g., processor nodes and I/O (input/output) nodes—to form a system area network. IBA is designed around a point-to-point, switched I/O fabric. Further, IBA defines hardware transport protocols that support reliable messaging as well as memory manipulation semantics—e.g., Remote Direct Memory Access (RDMA)—without software intervention in the data movement path.
The InfiniBand® specifications do not, however, adequately define how a conventional socket API (Application Program Interface)—or equivalent programming interfaces—can take advantage of the IBA hardware features. Therefore, although IBA eliminates the overhead associated with traditional TCP/IP stack processing, legacy applications designed for use with the socket API cannot take advantage of the reliability and performance offered by IBA. Further, the socket API itself may not expose the features of IBA to newer applications that have been designed to take advantage of the IBA hardware.